The present invention relates to an optical observation apparatus which enables an observer to observe an object image formed by light from an object through an eyepiece part, and more particularly to an optical observation apparatus which has a superimpose display function of superimposing an image for displaying various pieces of information on the object image. The optical observation apparatus of the invention is suitably used as an optical viewfinder mounted on an image-pickup apparatus such as a video camera or a still camera.
The optical viewfinder of the image-pickup apparatus has the superimpose display function of superimposing information images of focus detection areas or photometry areas on the object image in a finder viewing field to enable observation of both the images in the same viewing field.
Optical viewfinders that have the superimpose display function are disclosed in Japanese Patent Laid-Open Nos. 7-244317, 10-228057, and 2005-121732.
The optical viewfinder disclosed in Japanese Patent Laid-Open No. 7-244317 includes a display part constituted by reflective surfaces on a focusing screen. This display part is illuminated with light from a light source disposed in an upper front of a penta-dach prism. The reflected light from the display part is guided through the penta-dach prism to an eyepiece lens.
The optical viewfinder disclosed in Japanese Patent Laid-Open No. 10-228057 includes a light combining means such as a dichroic film disposed between a penta-dach prism and an eyepiece lens. The light combining means synthesizes an object image formed on a focusing screen and an image of information displayed on a liquid crystal panel to be superimposedly observed through the eyepiece lens.
The optical viewfinder disclosed in Japanese Patent Laid-Open No. 2005-121732 includes a collective lens which collects a light flux from a light source, a scanning member which scans and reflects the light flux transmitted through the collective lens, and a microlens array disposed near a position where an image is formed by the collective lens. An information image (electronic image) is formed on the microlens array with the light flux scanned by the scanning member. A superimposing means (polarization beam splitter) disposed in a viewfinder optical path synthesizes the object image formed on the focusing screen and the information image formed on the microlens array to be superimposedly observed.
In the optical viewfinder disclosed in Japanese Patent Laid-Open No. 7-244317, however, the reflective surfaces are formed beforehand on the focusing screen to constitute the display part, only predetermined information can be displayed.
In the optical viewfinders disclosed in Japanese Patent Laid-Open Nos. 10-228057 and 2005-121732, the arrangement of the light combining means and the superimposing means between penta-dach prism and the eyepiece lens extends the viewfinder optical path, which may cause a deterioration of viewfinder performance such as a reduction of a viewfinder magnification.